EN 15608:2008

Surface active agents - Quantitative determination of free fatty acid in alkylamidopropylbetaines - Gas-chromatographic method

This European Standard specifies a procedure for the determination of the content of free fatty acid, FFA, in alkylamidopropylbetaines, which is defined as being the amount of fatty acid expressed in grams per 100 g of product.
This method has been validated for the determination of fatty acids from C6 to C20 in a total concentration range from 0,02  g to more than 3,0 g fatty acid per 100 g of product.

Grenzflächenaktive Stoffe - Quantitative Bestimmung freier Fettsäure in Alkylamidopropylbetainen - Gaschromatographisches Verfahren

Diese Europäische Norm legt ein Verfahren zur Bestimmung des Massenanteils an freier Fettsäure, FFA, in
Alkylamidopropylbetainen fest, der als Menge an Fettsäure in Gramm je 100 g des Produkts definiert ist.
Validiert wurde dieses Verfahren zur Bestimmung von C6- bis C20-Fettsäuren in einem Gesamtkonzentrationsbereich
der Fettsäure je 100 g des Produkts von 0,02 g/100 g bis größer 3,0 g/100 g.

Agents de surface - Dosage quantitatif des acides gras libres dans les alkylamidopropylbétaïnes - Méthode par chromatographie en phase gazeuse

La présente Norme européenne spécifie un mode opératoire de détermination de la teneur en acides gras libres des alkylamidopropylbétaïnes, définie comme étant la quantité d’acides gras exprimée en grammes pour 100 g de produit.
La présente méthode a été validée pour le dosage des acides gras de C6 à C20 dans une plage de concentration totale allant de 0,02 g à plus de 3,0 g d’acides gras pour 100 g de produit.

Površinsko aktivne snovi - Kvantitativno določevanje prostih maščobnih kislin v alkilamidopropilbetainih - Metoda plinske kromatografije

General Information

• Status: Published
• Publication Date: 06-May-2008
• Withdrawal Date: 29-Nov-2008
• ICS: 71.100.40 - Surface active agents
• Technical Committee: CEN/TC 276 - Surface active agents
• Drafting Committee: CEN/TC 276/WG 1 - Methods of analysis
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 07-May-2008
• Due Date: 05-Sep-2009
• Completion Date: 07-May-2008
• Ref Project: SIST EN 15608:2008 - Surface active agents - Quantitative determination of free fatty acid in alkylamidopropylbetaines - Gas-chromatographic method

Overview

EN 15608:2008 (CEN) defines a validated gas‑chromatographic method for the quantitative determination of free fatty acid (FFA) in alkylamidopropylbetaines (surface active agents). The procedure reports FFA as grams per 100 g of product and is validated for fatty acids from C6 to C20 over a total concentration range of 0.02 g to >3.0 g FFA / 100 g product. The method combines acidic extraction, derivatisation to fatty acid methyl esters (FAME), and analysis by capillary GC with flame ionisation detection (GC‑FID).

Key Topics and Requirements

• Scope and validation: Applicable to alkylamidopropylbetaines; validated chain lengths C6–C20 and stated concentration range.
• Sample preparation:
  • Typical sample weight: 1.0 g (≈2.0 g when expected FFA <1 g/100 g).
  • Add water‑ethanol (1:1), acidify (0.5 mL HCl) to pH < 2, add internal standard, extract with petroleum ether (40–60 °C).
• Internal standard: Tridecanoic acid (0.3 g in 25 mL petroleum ether) used for quantification.
• Derivatisation:
  • Methylation performed with TMPAH (trimethylphenylammonium hydroxide) in the autosampler/injector (inject 2 µL at ≥310 °C).
  • Alternative liquid methylation with BF3/methanol noted as possible.
• GC analysis:
  • Capillary non‑polar column (e.g., HP‑1, 100% dimethylpolysiloxane) and FID.
  • Retention times must be established using a reference FAME mixture (C6–C20 including unsaturates).
• Calculation: Sum of areas of all fatty acid homologues related to the internal standard area; relative response factors assumed ≈1 for practical use (see annex for calibration guidance).
• Performance & recovery:
  • Single extraction average recovery ≈90%; three‑step extraction can achieve >97%.
  • Interlaboratory precision data (repeatability and reproducibility) and calibration considerations are included.

Applications and Users

• Laboratories performing QA/QC and specification testing of betaine surfactants.
• Surfactant manufacturers and formulators monitoring raw‑material or finished‑product FFA content.
• R&D groups developing surfactant formulations and analytical methods.
• Regulatory and conformity assessment bodies requiring standardized analytical procedures.

Practical Notes

• Use analytical‑grade reagents and water per EN ISO 3696.
• For coconut fatty‑acid distributions the method assumes relative response factors ~1; calibrate when fatty‑acid profiles differ.
• Annexes provide a reference chromatogram, GC conditions and interlaboratory validation data.

Related Standards

• EN ISO 3696 - Water for analytical laboratory use
• ISO 607 - Sample division for surface active agents and detergents
• ISO 5725‑2 - Precision (used in interlaboratory evaluation)

Keywords: EN 15608:2008, free fatty acid, FFA, alkylamidopropylbetaines, gas chromatography, GC‑FID, FAME, tridecanoic acid, TMPAH, surfactant analysis.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2008
3RYUãLQVNRDNWLYQHVQRYL.YDQWLWDWLYQRGRORþHYDQMHSURVWLKPDãþREQLKNLVOLQY
DONLODPLGRSURSLOEHWDLQLK0HWRGDSOLQVNHNURPDWRJUDILMH
Surface active agents - Quantitative determination of free fatty acid in
alkylamidopropylbetaines - Gas-chromatographic method
Grenzflächenaktive Stoffe - Quantitative Bestimmung freier Fettsäure in
Alkylamidopropylbetainen - Gaschromatographisches Verfahren
Agents de surface - Dosage quantitatif des acides gras libres dans les
alkylamidopropylbétaïnes - Méthode par chromatographie en phase gazeuse
Ta slovenski standard je istoveten z: EN 15608:2008
ICS:
71.100.40 Površinsko aktivna sredstva Surface active agents
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 15608
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2008
ICS 71.100.40
English Version
Surface active agents - Quantitative determination of free fatty
acid in alkylamidopropylbetaines - Gas-chromatographic method
Agents de surface - Dosage quantitatif des acides gras Grenzflächenaktive Stoffe - Quantitative Bestimmung freier
libres dans les alkylamidopropylbétaïnes - Méthode par Fettsäure in Alkylamidopropylbetainen -
chromatographie en phase gazeuse Gaschromatographisches Verfahren
This European Standard was approved by CEN on 11 April 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 15608:2008: E
worldwide for CEN national Members.

Contents
Foreword.3
1 Scope .4
2 Normative references .4
3 Principle.4
4 Reagents.4
5 Apparatus .5
6 Sampling and preparation of the test sample.5
7 Procedure .5
8 Calculation and expression of results.6
9 Precision.6
10 Test report .7
Annex A (informative) Reference GLC Chromatogram .8
A.1 GC Conditions.8
Annex B (informative) Method validation.9
B.1 Calibration .9
B.2 Statistical and other data derived from the results of interlaboratory tests .9
B.3 Remarks.10
Bibliography .11

Foreword
This document (EN 15608:2008) has been prepared by Technical Committee CEN/TC 276 “Surface active
agents”, the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2008, and conflicting national standards shall be withdrawn
at the latest by November 2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
1 Scope
This European Standard specifies a procedure for the determination of the content of free fatty acid, FFA, in
alkylamidopropylbetaines, which is defined as being the amount of fatty acid expressed in grams per 100 g of
product.
This method has been validated for the determination of fatty acids from C to C in a total concentration
6 20
range from 0,02 g to more than 3,0 g fatty acid per 100 g of product.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN ISO 3696, Water for analytical laboratory use – Specification and test methods (ISO 3696:1987)
ISO 607, Surface active agents and detergents – Methods of sample division
3 Principle
The free fatty acids are extracted with petroleum ether at acidic pH. Then the extracted fatty acids are
derivatised and subsequently analysed by GLC-FID. The chromatogram resolves the different acids according
to their alkyl chain length. For quantification the sum of the peak areas of all fatty acid homologues is related
to the peak area of the internal standard tridecanoic acid.
4 Reagents
4.1 General
WARNING — Your attention is drawn to the regulations covering the handling of hazardous
substances. Technical, organisational and personal protection measures should be observed.
During the analysis, unless otherwise specified, use only reagents of recognized analytical grade and that
have been checked in advance as to not interfere with the analytical results and water complying with grade 1
as defined in EN ISO 3696.
4.2 Tridecanoic acid, purity ≥ 99 % (m/m) (CAS number: 638-53-9).
4.3 Petroleum ether (40 ºC to 60 ºC) (CAS number: 101316-46-5).
4.4 Ethanol (CAS number: 64-17-5).
4.5 HCl, c = 37% (m/m) (CAS number: 7647-01-0).
4.6
...